My wife's income on T4 is in box 71 not 14 ....so return won't accept because box 18 (ei) exceeds income. What do I do?

You need to ensure you have entered an amount in Box 24 - EI Insurable Earnings if the employer has withheld EI Premiums in Box 18. 

You may want to contact the employer or payroll department to verify the number that should be in Box 24. It may or may not be the same as the Box 71 amount (or the maximum of $51,700), and only the employer can tell you what the exact figure is that belongs there.